**12. ITGAM gene and SLE**

ITGAM produces macrophage antigen 1(MAC1), an adhesion molecule found on the surface of myeloid cells, natural killer cells and a subgroup of B cells. This is achieved when CD11b-integrin Am - encoded by ITGAM - is united to C818-integrin β2. Leucocyte adhesion and migration may be influenced by MAC1 as it binds to intercellular adhesion molecules - ICAM1 and ICAM2. In addition, MAC1 is a receptor for the cleaved complement factor IC3b. A polymorphism of this gene, particularly the R77H - a single nucleotide polymorphism -(SNP), is associated with SLE by modifying the structure of the gene products. This results in an increased production of proinflammatory cytokines and a reduced Ic3b phagocytosis and cellular adhesion. This makes this polymorphism a probable therapeutic target for lupus treatment. ITGAM gene polymorphisms result in defective clearance of immune complexes and apoptotic cells and lead to initiation and maintenance of autoimmune responses and chronic inflammation in SLE. ITGAM gene polymorphisms are associated with increased susceptibility to CCLE rather than to SLE [26].
